JPH0347417A - Lubricating device for four-cycle engine - Google Patents

Abstract

PURPOSE:To prevent flowout of lubricant out of rush adjuster when the engine has stopped by furnishing a divergent passage diverging to the bearing part of a cam shaft on a main passage connecting the rush adjusters on the suction and exhaust sides. CONSTITUTION:An oil passage in a head cover 3 and a cylinder head 2 is composed of a main passage 66 connecting a rush adjuster 30 on the suction valve side to a rush adjuster 30 on the exhaust valve side and a supply path 57 tying this main passage 66 to a pump 56. On the main passage 66 a divergent passage 68 is furnished diverging for the journals 5b, 6b of cam shafts 5, 6. When the lubricant is returned to the oil pump 56 side associated with stop of the engine, the communication with the rush adjusters 30 and the supply path 57 is closed at distribution passages 59a, 59b. Accordingly much lubricant remains within the rush adjusters 30 even when the engine has stopped.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides an overhead cam-type four-stroke engine equipped with a rocker arm, in which lubricating oil is applied to a hydraulic lash adjuster that supports the rocker arm and a bearing of a camshaft. Regarding lubrication equipment that guides

[Prior Art] Conventionally, for example, ``Japanese Unexamined Patent Publication No. 113512/1983'' discloses a so-called DOHC type four-stroke engine in which a cylinder head is provided with two camshafts for intake and exhaust. There is. In this engine, a plurality of intake valves and exhaust valves are each linked to a camshaft via a rocker arm, and the rocker arm is supported by a cylinder head via a rocker shaft and a hydraulic lash adjuster.

By the way, the lash adjuster that supports this rocker arm is for automatically zero-adjusting the tappet clearance between the rocker arm and the valve stem, and its specific configuration is disclosed in, for example, the Japanese Utility Model Application No. 64-53406.
It is disclosed in "No.

That is, this type of lash adjuster includes a body that is embedded in the cylinder head and a plunger that is slidably inserted into the body in the axial direction, and the tip of the plunger is in contact with one end of the rocker arm. . A high pressure chamber is formed between the bottom of the body and the plunger, and this high pressure chamber is connected to a reservoir chamber inside the plunger via a check valve. The reservoir chamber is connected to the oil passage on the cylinder head side through an introduction hole made in the body, and lubricating oil from the oil pump is supplied to the reservoir chamber and high pressure chamber through this oil passage. .

Therefore, while the engine is running, the plunger is constantly pressed against the rocker arm by the hydraulic pressure in the high pressure chamber.
This keeps the fulcrum position of the rocker arm constant.

On the other hand, in a DOHC type engine, the cylinder head is provided with a bearing portion that receives the journal portion of the camshaft. An oil supply port for supplying lubricating oil is opened in this bearing portion, and conventionally, this oil supply port has been connected in series to the reservoir chamber of the lash adjuster through an oil passage in the cylinder head.

For this reason, the lubricating oil sent from the oil pump is configured to be guided to the oil filler port after passing through the reservoir chamber of the lash adjuster, from where it flows out through the clearance between the bearing part and the journal part. ing.

[Problems to be Solved by the Invention] By the way, the oil filler port, which is the downstream end of the oil passage, is open to the atmosphere through the clearance between the bearing part and the journal part. In addition, when negative pressure is generated in the upstream portion of the oil passage on the oil pump side, the lubricating oil filled in the oil passage is gradually returned to the oil pump side.

For this reason, if the oil filler port and the lash adjuster are connected in series as in the past and the lubricating oil is guided to the oil filler port via the reservoir chamber of the lash adjuster, the reservoir chamber will drain over time when the engine is stopped. The lubricating oil in the room is also gradually returned to the oil pump side.

Particularly when the engine is stopped for a long period of time, much of the lubricating oil in the reservoir chamber leaks out, leaving the reservoir chamber empty, and when the engine is restarted, the reservoir chamber and high pressure chamber become empty. It will take a considerable amount of time for the oil pressure to recover.

Therefore, even after the engine starts, the tappet clearance cannot be adjusted to zero lash for a while.
There is a problem with tappet noise.

The present invention was made based on these circumstances, and
To provide a lubricating device for a four-stroke engine, which can prevent lubricating oil in a lash adjuster from flowing out when the engine is stopped and allows good oil pressure recovery when restarting the engine.

[Means for Solving the Problems] Therefore, in the present invention, an intake valve and an exhaust valve are provided in the cylinder head, and these intake valves and exhaust valves are connected to an intake camshaft and an exhaust camshaft, respectively, via a rocker arm. At the same time, one end of the rocker arm is supported by a cylinder head via a hydraulic lash adjuster, and an oil passage is provided in the cylinder head to guide lubricating oil sent from the oil pump to the lash adjuster and the bearings of each camshaft. In the four-stroke engine, the oil passage is composed of a main passage connecting a lash adjuster on the intake valve side and a lash adjuster on the exhaust valve side, and a supply passage connecting the main passage with the oil pump. This main passage is characterized by providing a branch passage branching toward the bearing portion of the camshaft.

[Function] According to this configuration, when negative pressure is generated in the upstream portion of the oil passage on the oil pump side when the engine stops, the branch passage connected to this oil passage is connected to the oil passage between the bearing and the camshaft. Because it is exposed to the atmosphere through a clearance,
Atmospheric pressure acts on the opening end of this branch passage to the bearing section.1. :Become. Therefore, the lubricating oil that has filled the oil passage is gradually returned to the oil pump side.

In this case, the branch passage is branched from the main passage connecting between the lash adjusters on the intake side and the exhaust side, and the supply passage leading to the oil pump is also connected to the main passage without passing through the lash adjuster. The lubricating oil returned from the branch passage to the main passage continues along the supply passage and is returned to the oil pump side. When the curved surface of this lubricating oil passes through the connection between the main passage and the supply passage, the upstream side of the lash adjuster becomes atmospheric pressure, so that the communication between the lash adjuster and the supply passage becomes the connection between the supply passage and the main passage. The lubricating oil inside the lash adjuster can be prevented from flowing out to the oil pump side.

Therefore, even when the engine is stopped, much of the lubricating oil remains in the lash adjuster, and when the engine is restarted, the oil pressure in the lash adjuster is immediately restored.

[Example] The f? of the present invention is as follows. The Jl embodiment will be explained based on FIGS. 1 to 10, in which it is applied to a four-stroke multi-cylinder engine.

In FIG. 3, reference numeral 1 indicates a cylinder block, 2 indicates a cylinder head, and the upper surface 2a of the cylinder head 2 is covered with a head cover 3. A valve train chamber 4 is formed between the cylinder head 2 and the head cover 3. In this valve operating chamber 4, an intake camshaft 5 and an exhaust camshaft B are housed parallel to each other.

A sprocket 7 is fixed to one end of each of the intake camshaft 5 and the exhaust camshaft B, and a timing chain 8 is passed between these sprockets 7. Further, a timing pulley 9 is fixed to the other end of the exhaust camshaft 6, and this timing pulley 9 is interlocked with a crankshaft (not shown) via a timing belt 10. Therefore, in the case of this embodiment, the intake camshaft 5 is rotationally driven by power transmission from the exhaust camshaft 6.

Inside the cylinder block 1, a plurality of cylinders 11 are arranged side by side along the axial direction of the crankshaft. On the white surface of the cylinder head 2 which is superimposed on this cylinder block 1,
A recess 13 is formed which defines a combustion chamber 12 in the form of a vent roof. The recesses 13 are provided corresponding to the cylinders 11, and each of the four parts 13 has three intake ports 14a, 14b, L4c and two exhaust ports 1, as shown in FIG.
5a and 15b are open. These intake ports 14a
, 14b, 14c and the exhaust ports 15a, 15b are provided at positions sandwiching a reference line A1 that passes through the bore center X1 of the cylinder 11 and extends in the axial direction of the camshaft 5.6,
A plug mounting hole 16 is opened above the bore center Xl.

Further, this cylinder head 2 is connected to the cylinder block 1 via head bolts I7.

As shown in FIGS. 1 and 5, the head bolt 17 is
The intake camshaft 5 and the exhaust camshaft B are arranged side by side in one row, and are located inside of both of these camshafts 5.6.

Intake ports 14a, 14b, 14c of cylinder head 2
are individually opened and closed by three intake valves 19a, 19b, and 19c, and exhaust ports 15a and 15b are also individually opened and closed by two exhaust valves 20a and 20b. Valve stems 21, 22 of these intake valves 19a, 19b, 19c and exhaust valves 20a, 20b.
is supported by the cylinder head 2 via a valve guide 23, and the upper end portions of the valve stems 21 and 22
As shown in the figure, it penetrates the cylinder head 2 and is introduced into the valve train chamber 4.

These intake valves 19a, 19b, 19c and [L valves 20a, 20b have their valve stems 21
, 22 are led out parallel to each other along a direction orthogonal to the intake camshaft 5 and the exhaust camshaft 8, and are arranged in parallel in the axial direction of these camshafts 6.6. Three intake valves 1
Among 9a, 19b, and 19e, the central intake valve 1
9b is offset to the outside in the radial direction of the combustion chamber 12 with respect to the intake valves 19a and 19c on both sides. Therefore, the inclination angle α1 of the center intake valve 19b with respect to the bore center line X2 is as shown in FIG.
The inclination angle α2 of these three intake valves 19a and 19b is set smaller than the inclination angle α2 of these three intake valves 19a and 19b.

The upper end of the valve stem 21 of 19c is located at the reference line AI.
It is located on a straight line between the roads parallel to the road.

Note that a plug insertion hole 24 is formed in the cylinder head 2 and head cover 3 and is connected to the plug mounting hole 16, and this plug insertion hole 24 connects the intake valves 19a, 19b, 19c and exhaust valves 20a, 2 of each cylinder 11.
0b.

On the other hand, the intake camshaft 5 includes three intake cams 2B for each cylinder, and the exhaust camshaft 8 includes two exhaust cams 27 for each cylinder. These camshafts 5 and 6 are connected to intake valves 19a, 19b, 1
9c and the axes Y1 and Y2 of the exhaust valves 20a and 20b
Since the intake cam 26 is provided at a position apart from the intake cam 26,
The exhaust cam 27 is in contact with the valve stems 21, 22 of the intake valves 19a, 19b, 19c and the exhaust valves 20a, 20b via a rocker arm 28, respectively.

The rocker arm 28 has a hydraulic lash adjuster 8 at one end opposite to the contact portion of the valve stems 21 and 22.
Supported by 0. This lash adjuster 3
0, as shown in FIG. 2, has a cylindrical body 31;
A plunger 32 is fitted into the body 31 so as to be slidable in the axial direction. A reservoir chamber 33 is formed inside the plunger 32;
is connected to a supply hole 34 formed in the body 31.

A high pressure chamber 3 is provided between the bottom surface of the body 31 and the plunger 32.
5 is formed. The high pressure chamber 35 is connected to the reservoir chamber 33 via the communication port 3B at the bottom of the plunger 32. Inside the high pressure chamber 35, there is a normally closed check valve 37 that opens and closes the communication port 3B, and a check valve 37 that opens and closes the communication port 3B. A biasing spring 3B is housed. The tip of the plunger 32 is formed into a spherical shape, and the rocker arm 2
The plunger 32 is fitted into a recess 39 at one end of the plunger 32, and an oil supply hole 40 connected to the reservoir chamber 33 is formed at the tip of the plunger 32.

Such a lash adjuster 30 is connected to the intake valves 19a, 19b, 19c and the exhaust valve 2, which are interlocked with each other.
0a.

20b, and its body 31 is fitted and held in a mounting hole 41 formed in the upper surface 2a of the cylinder head 2.

Further, the intake camshaft 5 and the exhaust camshaft 6 are supported by the cylinder head 2 at a plurality of locations between both ends thereof and the intake valves 19a, 19b, and 19c.

That is, on the upper surface 2a of the cylinder head 2, there are two end bearing parts 44 that receive the journal parts 5a and 6a at both ends of each camshaft 5.6, a journal part 5b between the adjacent intake cams 26, and a journal part 5b between the exhaust cams 27. An intermediate bearing portion 45 for receiving the journal portion 6b is provided in a protruding manner. Intermediate bearing part 4
5, both camshafts 5°6 between adjacent intake valves 19a, 19b, 19c and exhaust valves 20a, 20b.
The intermediate bearing portion 45 and both end bearing portions 44 have respective journal portions 5a, 5 on the upper surfaces thereof.
A fitting recess 4B is formed in which the fittings b, 8a, and 8b are rotatably fitted.

Cam caps 47 are placed on the upper surfaces of both end bearing portions 44 and intermediate bearing portion 45, respectively. cam cap 47
between the fitting recess 46 and the journal portions 5a, 5b,
[ia and 8b are provided with another fitting recess 48 that rotatably supports them. These cam caps 47 are integrally protruded from the inner surface of the head cover 3, and the head cover 3 is fastened to the bearing portions 44 and 45 via bolts 49 at the position of the cam caps 47. .

For this reason, a plurality of insertion holes 50 are opened in the upper surface of the head cover 3 to allow the bolts 49 to pass therethrough.

Incidentally, an oil passage 55 for supplying lubricating oil to the lash adjuster 30 and the bearing portions 44, 45 of each camshaft 5.6 is formed inside the cylinder head 2. Details of this oil passage 55 will be described below. I will explain about it.

That is, as shown in FIGS. 1 and 5, a supply path 57 is formed inside the cylinder block 2 and is connected to the oil pump 56. The supply path 57 extends vertically at a position biased toward the intake camshaft 5 side, and its upper end portion is led to a position approximately at the same height as the lash adjuster 30 on the intake side. On the left and right side walls 58 on the cylinder head 2 side that form the valve chamber 4, there are lash adjusters 30 on the intake side.
and distribution passages 59a, 5 located outside the lash adjuster 30 on the exhaust side and extending in the axial direction of the camshaft 5.6.
9b is formed. A portion of the distribution passages 59a, 5'lb is a mounting hole 41 into which the lash adjuster 30 is fitted.
distribution passages 59a, 59 in this penetrating portion.
A communication port 60 is formed that communicates b and the mounting hole 41. The communication ports 60 of the distribution passages 59a and 59b are connected to the supply hole 34 of the lash adjuster 30,
Of the distribution passages 59a and 59b, the distribution passage 59a on the intake side is connected to the upper end of the supply passage 57 via a communication passage 61.

Further, a first oil flow passage 68 extending in a direction perpendicular to the camshaft 5.6 is formed in the earth wall portion 62 that constitutes the upper surface of the head cover 3. As shown in FIGS. 6 and 9, the first oil flow passage 63 is located between the plug insertion holes 24, and both ends of the first oil flow passage 83 are connected to the camshaft 5.
．． It is passing above 6.

The left and right sides 984 of the head cover 3 and the side of the cylinder head 2 connected to this side wall 64! 258 are formed with delivery passages 65a and 65b extending in the vertical direction.
.

59b and the first oil flow passage 63 are communicated with each other. Therefore, in the case of this embodiment, the first oil flow passage 63 and the delivery passages 65a and fi5b constitute a main passage 6B that connects the lash adjusters 30 on the intake side and the exhaust side, and the downstream end of this main passage 6B. The distribution passage 59b on the exhaust side connected to
It is closed without opening into the valve train chamber 4.

Second oil flow passages B7a and θ7b are formed in the earthen wall portion 62 of the head cover 3, and extend directly above each camshaft 5, 6 in the axial direction of the camshaft 5.8. Second oil flow passage f
17a and 87b are the first oil flow passages 6 inside the earthen wall part B2.
3, and both these passages 63.87a, 67
b are in communication with each other. Second oil flow passage 67a.

87b is branched downward at the position of the cam cap 47, and these branch passages 68 are connected to the upper surface of the fitting recess 48 in contact with the journal parts 5a, 5b, 6a, and 8b. It is opened to For this reason,
The plurality of branch passages 68 are individually branched from the main passage 66, as schematically shown in FIG. 7, and are located between the lash adjusters 30 on the intake side and the exhaust side.

Note that reference numeral 70 in FIG. 1 is a lubricating oil return passage that opens at the bottom of the valve operating chamber 4, and this return passage 70 is connected to an oil pan (not shown).

Next, the operation of the above configuration will be explained.

When the engine is started, the lubricating oil sent out from the oil pump 56 is first supplied to the intake side distribution passage 59a through the supply passage 57 and the communication passage 61, and from there through the communication port BO and the supply hole 34 to the intake air. It flows into the reservoir chamber 33 and high pressure chamber 35 of the lash adjuster 30 on the side.

Furthermore, the lubricating oil in the distribution passage 59a is transferred to one delivery passage 65.
a into the first oil flow passage 63, and from there through the other delivery passage 85b to the exhaust side distribution passage 5.
9b. The lubricating oil in this distribution passage 59b is
Similarly to the intake side, it flows into the reservoir chamber 33 and high pressure chamber 35 of the lash adjuster 30 on the exhaust side through the communication port 60 and the supply hole 34, and both these chambers 33.3
5 oil pressure is increased.

The lubricating oil in the first oil flow passage 63 is transferred to the second oil flow passage a7.
a, 67b, and from there flows into the journal portions 5a, 5b, 6a, O of each camshaft 5.8 through a branch passage 68.
b. This lubricating oil is then applied to the journal portion 5.
a, 5b, 6a, 6b and the fitting recesses 4B, 48 flow into the valve operating chamber 4, and this valve operating chamber 4
The oil is returned to the oil pan through a return passage 70 that opens at the bottom of the oil pan.

By the way, when the engine operation is stopped, negative pressure is generated in the upstream portion of the supply path 57 on the oil pump 56 side. Then, since the branch passages 68 branched from the main passage 6B are open to the atmosphere through the clearances between the journal parts 5a, 5b, Ba, 6b and the fitting recesses 4B, 48, the distribution passages 68 are Atmospheric pressure acts on the opening to the fitting recess 48, and the second oil flow passage 67a,
67b, the lubricating oil filling the main passage 66 and the supply passage 57 gradually begins to return to the oil pump 56 side.

In this case, the distribution passage 59b connected to the lash adjuster 30 on the exhaust side is located downstream of the branch passage B8 connected to the exhaust camshaft 6, and furthermore, the distribution passage 59b is closed without opening into the valve train chamber 4. Therefore, the lubricating oil guided into the lash adjuster 30 on the exhaust side remains as it is.

On the other hand, since the intake side lash adjuster 30 is located between the oil pump 5B and the branch passage 88,
There is a possibility that the lubricating oil within the lash adjuster 30 may also be returned to the oil pump 56 side as time passes.

However, the main passage 68 configured as described above is provided without penetrating the lash adjuster 30 on the intake side. In other words, the supply hole 34 of the lash adjuster 30 is branched from the communication port 60 of the distribution passage 59a. Since they are continuous, the lubricating oil returned from the first oil flow passage 63 to the distribution passage 59a is returned to the oil pump 56 side through the distribution passage 59a. When the liquid level of the lubricating oil passes through the opening of the communication port 60, the pressure at the opening of the communication port 60 becomes atmospheric, so that the communication between the supply hole 34 of the lash adjuster 30 and the distribution passage 59a is established through the communication port 60. 60 openings will be closed.

Therefore, the lubricating oil in the lash adjuster 30 on the intake side can be prevented from flowing out to the oil pump 5B side, and even when the engine is stopped, most of the lubricating oil remains in the reservoir chamber 33 of the lash adjuster 30. become.

Therefore, when the engine is restarted, the oil passage 5
The air in each part in the journal parts 5a and 5b.

6a, 6b and the fitting recesses 4B, 4g, it is discharged through the clearance between the reservoir chamber 33 and the high pressure chamber 35.
The oil pressure will be restored immediately, and after starting,
Tappet clearance can be immediately adjusted to zero lash.

Moreover, if lubricating oil remains in the reservoir chamber 33 and the high pressure chamber 35, the oil film on the sliding part between the body 31 and the plunger 32 will not be interrupted, and this sliding part can be reliably lubricated. .

Further, in the case of the above embodiment, there are three lash adjusters 30 per cylinder on the intake side and two on the exhaust side, but the lubricating oil from the oil pump 56 is first supplied to the lash adjuster 30 on the intake side. As a result, variations in the hydraulic pressure acting on a total of five lash adjusters 30 can be suppressed.

Further, since the lash adjuster 30 and the journal portions 5a, 5b, 6a, and 8b of the camshafts 5 and 6 are connected to the main passage 66 while being branched from the main passage 66, the communication port 60 and the branch passage 88 By simply increasing or decreasing the diameter of the lash adjuster 30 and journal parts 5a and 5b.

There is an advantage that the hydraulic pressure acting on 8a and 8b can be freely changed.

Further, a distribution passage 59a on the intake side and a distribution passage 5 on the exhaust side
9b is provided in the head cover 4, the dimensions of the cylinder block l and the cylinder head 2 in the camshaft 5.8 direction can be shortened.

That is, the first oil flow passage 63 is connected to the cylinder head 2.
When provided on the side, this first oil flow passage 83 is connected to a plurality of cylinders 1.
1, so the first oil flow passage 6
It is necessary to widen the arrangement interval of the cylinders 11 by a dimension corresponding to the diameter of 3, and the overall length of the cylinder block 1 and cylinder head 2 increases accordingly.

Since there is no need to secure space, the spacing between the cylinders 11 can be narrowed, and the cylinder block l and cylinder head 2 can be made more compact.

In the first embodiment, the lash adjuster and branch passage on the intake side and the lash adjuster and branch passage on the exhaust side are provided in series with the oil pump 5B.
The present invention is not limited to this. For example, as in the second embodiment of the present invention shown in FIG.
and branch passage B8 and exhaust side lash adjuster 30
The branch passage 68 may also be provided in parallel to the oil pump 56.

Furthermore, the number of intake valves and exhaust valves per cylinder is not limited to the above embodiment, for example, two intake valves and two exhaust valves may be provided per cylinder, and the number of cylinders is not limited to multiple cylinders. , it may be a single cylinder.

In a single-cylinder engine having one intake valve and one exhaust valve, one lash adjuster may be provided on the intake side and one on the exhaust side, so the distribution passage as in the above embodiment is not necessary.

[Effects of the Invention] According to the present invention described in detail above, even when the engine is stopped, much of the lubricating oil remains inside the lash adjuster, so when the engine is restarted,
The oil pressure in the lash adjuster will be restored immediately. Therefore, even after starting, the tappet clearance can be immediately adjusted to zero lash, suppressing tappet noise and enabling quiet operation.

[Brief explanation of drawings]

1 to 1V show a first embodiment of the present invention, in which FIG. 1 is a sectional view of the cylinder head and its surroundings, FIG. 2 is a sectional view of the lash adjuster, and FIG. 4 is a sectional view taken along line IV-IV in FIG. 5, FIG. 5 is a plan view of the cylinder head, FIG. 6 is a plan view of the head cover, and FIG. 7 is a schematic diagram showing an outline of the oil passage, FIG. 8 is a cross-sectional view taken along the line ■-■ in FIG. 4, FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. 6,
FIG. 10 is a schematic configuration diagram of a combustion chamber, and FIG. 11 is a schematic diagram showing an outline of an oil passage in a second embodiment of the present invention. 2
...Cylinder head, 5...Intake camshaft, 6...
- Exhaust camshaft, 19a, 19b, 19c... Intake cam, 20a, 20b... Exhaust valve, 28... Rocker arm, 30... Lash adjuster, 55...
Oil passage, 57... Supply passage, 66... Main passage, 6
8... Branch passage.

Claims (1)

[Claims] The cylinder head is provided with an intake valve and an exhaust valve, and these intake valves and exhaust valves are linked to an intake camshaft and an exhaust camshaft through a rocker arm, respectively, and one end of this rocker arm is connected through a hydraulic lash adjuster. In a four-cycle engine, the cylinder head is supported by a cylinder head, and an oil passage is formed in the cylinder head to guide lubricating oil sent from an oil pump to the lash adjuster and the bearings of each camshaft. It consists of a main passage that connects the lash adjuster on the valve side and the lash adjuster on the exhaust valve side, and a supply path that connects this main passage and the oil pump. A lubrication device for a four-cycle engine, characterized in that a branch passage is provided.